<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			* {
				margin: 0;
				padding: 0;
			}
			#container {
				width: 940px;
				height: 430px;	
				margin: 0 auto;
			}
		</style>
	</head>
	<body>
		<!-- 绑定事件除了用标签属性之外还有哪些更好的做法 -->
		<div id="container" onmouseover="stopChange()" onmouseout="resumeChange()">
			<img id="adv" src="img/slide-1.jpg"> 
		</div>
		<script>
			// 除了getElementById还有哪些获取元素的方法
			// - getElementsByTagName()
			// - getElementsByClassName()
			// - querySelector()
			// - querySelectorAll()
			var img = document.getElementById('adv');
			var currentIndex = 0;
			var timerId = 0;
			
			resumeChange();
			
			function stopChange() {
				window.clearInterval(timerId);
			}
			
			function resumeChange() {
				timerId = setInterval(function() {
					currentIndex += 1;
					currentIndex %= 4;
					img.src = 'img/slide-' + (currentIndex + 1) + '.jpg';
				}, 3000);
			}
		</script>
	</body>
</html>
